Wiper motor replacement

I have a 1998 Legacy Outback. The rear wiper motor appears to have died or the linkage is frozen. There is power at the electrical plug going to the wiper motor but the wiper does not move. The manual says to remove the rear wiper from its spindle. Sounds simple enough! I have removed the cap and the bolt that hold the wiper on but the wiper will not budge. I have tried a gear puller but no luck. I am afraid to heat the base of the wiper arm in case I melt the parts under it or crack the rear window. I was thinking of taking a grinder to it. Any suggestions?

thanks